Since the end of the 20th century the cellular telephone industry has had enormous development in the world. From the initial analog systems, such as those defined by the standards AMPS (Advanced Mobile Phone System) and NMT (Nordic Mobile Telephone), the development has during recent years been almost exclusively focused on standards for digital solutions for cellular radio network systems, such as D-AMPS (e.g., as specified in EIA/TIA-IS-54-B and IS-136) and GSM (Global System for Mobile Communications). Different digital transmission schemes are used in different systems, e.g. time division multiple access (TDMA) or code division multiple access (CDMA). Currently, the cellular technology is entering the so called 3rd generation, providing several advantages over the former, 2nd generation, digital systems referred to above. Among those advantages an increased bandwidth will be provided, allowing effective communication of more complex data. The 3rd generation of mobile systems have been referred to as the UMTS (Universal Mobile Telephony System) in Europe and CDMA2000 in the USA, and is already implemented in Japan to some extent. Furthermore, it is widely believed that the first generation of Personal Communication Networks (PCNs), employing low cost, pocket-sized, cordless telephones that can be carried comfortably and used to make or receive calls in the home, office, street, car, etc., will be provided by, for example, cellular carriers using the next generation digital cellular system infrastructure.
A lot of effort has been made in making smaller terminals, with much help from the miniaturisation of electronic components and the development of more efficient batteries. In only a couple of decades the communication systems have gone from analogue to digital, and at the same time the dimensions of the communication terminals have gone from briefcase size to the pocket size phones of today. Today, numerous manufacturers offer pocket-sized terminals with a wide variety of capabilities and services, such as packet-oriented transmission and multiple radio band coverage. Still today, mobile phones are getting smaller and smaller and the size is generally considered to be an important factor for the end customer. The development in electronics has made it possible to miniaturise the components of the terminals, at the same time making the terminals capable of performing more advanced functions and services. The development of new transmission schemes, the so-called 3rd generation mobile system standing at the door and the 4th generation to be expected maybe ten years later, also provides the possibility to convey more advanced data to the wireless communication terminals, such as real time video.
The end users have a number of conflicting requirements on the mobile phones. Basically, the terminal should be as small and light-weight as possible. Furthermore, is should provide more and more advanced functions, have a long battery time, and a user-friendly interface. As technology advances, new or previously implemented features can be miniaturised, rendering smaller terminals. This concerns e.g. battery technology and electronics. Still, there is only so much space in a terminal, and in order to be competitive the elements of the terminal must be carefully packaged. Built-in antennas of different types have eliminated the need for protruding antenna elements, but the most frequently used type of built-in antennas, the so called PIFA (Planar Inverted-F Antenna), will instead add to the height of the terminal since it must be placed a certain distance from the PCB ground plane in order to provide a sufficient bandwidth.
A trend within the fields of mobile telephony and pocket computers such as Personal Digital Assistants PDA:s, is to implement larger displays serving as data output interfaces. This is particularly interesting with the transmission schemes which make it possible to transmit and present video. Furthermore, such displays may also be touch-sensitive and serve as data input interfaces, preferably operated by means of a pen-like member. Still, it is recognised that many users prefer the traditional keypad, at least as a complement to the touch-sensitive display, with distinct separate keys which in many cases are considered to be easier to operate with the fingers. However, the keypad has the disadvantage of occupying space on a face surface of the terminal, space that e.g. could have been used to implement a larger display.